Bi-axial Stress/Strain Measurement

Hyperelastic material behaviour requires investigation of basic physical parameters. Biaxial testing of rubber-like materials can be tested in several stress-strain modes so that the material properties are correctly defined. This alaso is needed so that the multiaxial deformation can be accurately modelled using FEA software. The strain energy of polymeric materials can be expressed by three strain invariants. The second stress invariant has greater influence on the stress-strain multiaxial deformation, so biaxial test data is required to ensure the quality of the material model.

  
We have two specialised seal material testing rigs for conducting biaxial tests on highly non-linear polymeric materials. The rigs are designed for inflating rubbers with thickness varying from 80µm to 2mm. The biaxial test capabilities are summarised below:

• Pressure rigs for clamping the material of interest.
• Pressure and temperature transducers.
• Cameras and video editing software for post-processing images.
• Computers linked with the instrumentation using data acquisition system (DAS).
• Analysis of the recorded data using DAQ software.